Trutaieva I. Effect of cryopreservation on morphofunctional properties of ovarian tissue.

The research object was the cryoinjury of ovarian tissue fragments during adding/removing, freezing-warming and subsequent heterotopic transplantation. The research aim was to investigate the morphological transformations and biochemical characteristics of ovarian tissue in vitro, as well as the dynamics of folliculogenesis and steroidogenic function in vivo, depending on the composition of the media at the adding/removing stage, type and concentration of the cryoprotectant agents (CPA), as well as the freezing regime. Research methods were as follows: morphometric; spectrophotometric; programmable freezing; heterotopic transplantation; photocolorimetric; chemiluminescent immunoassay; cytological analysis; statistical analysis of the results. Theoretical and practical results, scientific novelty: It has been proven that preservation of the maximum follicle pool after ovarian tissue cryopreservation was possible under the conditions of selection of the freezing mode in relation to the type and final concentration of CPA. The selection of freezing mode contributed to the reduction of the toxic effect of 3.0 M DMSO and the degree of ovarian tissue damage by ice crystals in the case of 1.5 M PROH. The use of solutions of 1.5 M DMSO and 3.0 M PROH showed a high level of follicles preservation in the process of freezing-warming, regardless of the used freezing regimes. It was shown for the first time that after grafting of cryopreserved ovarian tissue, the restoration of endocrine function and the normalization of lipid metabolism indices in ovariectomized recipient animals were achieved with the use of 3.0 M PROH or 3.0 M DMSO in combination with osmotically active compounds in cryoprotective solution: sucrose (at saturation) and mannitol (during CPA removing). Practical significance consist in the fact that the obtained results can be used in the research field of biotechnology, endocrinology, reproductive and experimental medicine. Sphere of application covers: the educational process in educational institutions for the training of specialists in various fields of biology, in particular, cryobiology, and agricultural sciences.